Fluorocarbon vinyl-type esters and polymers



United States Patent 0.

' FLUOROCARBON VINYL-TYPE ESTERS AND POLYMERS N Drawing. ApplicationDecember 29, 1955 Serial No. 556,074

4 Claims. ((11.260-793) This invention relates to our discovery of a newand useful class of fluorocarbon vinyl-type esters and their polymers.The invention provides polymers which have notable utility for sizingcloth to impart both water repellency and resistance to absorption andstaining by oils and greases. These esters and their polymers also haveutility for other surface treating or coating usages to obtain bothwater and oil repellency, and the esters have utility as surface activeagents.

More particularly, these novel ester compounds, are vinyl esters andallyl esters of perfluoroalkanesulfonamido alkylenemonocarboxylic acidswhich have in the molecule aperfluorocarbon tail containing-4 to 12fully fluorinated carbonatoms. I

The vinyl esters have the equivalent general formulas:

The allyl esters are also vinyl-type esters, having a terminal vinylgroup (CH=CH but-are the nexthi'gher homologues ofthe correspondingsimple vinyl esters shown in the above formulas. They have in themolecule a methylene linking group to which the terminal vinyl group isjoined, as shown by the equivalent general formulas corresponding tothose shown above:

Inthese formulas R 'is a perfluoroalkyl group containing 4 to 12 carbonatoms (which provides the perfluorocarbon tail), R is an alkylenebridging group containing 1 to '12' carbon atoms, and R is a hydrogenatom or an alkyl group containing 1 to 6 carbon atoms (methyl, ethyl,propyl, butyl, amyl or hexyl).

The aforesaid acids of which these esters are derivatives, have theformula: q

R SO N(R')RC0OH These acids may be regarded as N-substituted derivativesof amino acids of the monoamino-monocarboxylic type' (H NRCOOH) in whichone N-bonded hydrogen atom is replaced by a perfluoroalkanesulfonylgroup (R;SO and the other hydrogenatom may or may not be replaced by ashort-chain alkyl group. An example" H C F SO N(C H )CH COOH Thiscompound is sonamed because it may be regarded as a derivative ofglycine, an amino acid having the formula H NCH COOH. It has a terminalperfluoro- 2? alkyl group which provides a perfluorocarbon tailcontaining eight fully fluorinated carbon atoms.

The perfluorocarbon tail structure may include an oxygen atom linkingtogether two perfluorinated carbon atoms, or a nitrogen atom linkingtogether three per fluorinated carbon atoms, since these linkages arevery stable and do not impair the inert and stable fluorocarboncharacteristic of the structure (cf., U. S. Patents Nos. 2,500,388 and2,616,927).

Perfluoroalkanesulfonyl compounds useful as starting compounds formaking the present vinyl-type esters have been described in thecopending application of T. I. Brice and P. W. Trott, S. N. 448,784,filed Aug. 9, 1954, and issued as Patent No. 2,732,398 on Jan. 24, 1956.

It is of critical importance that the perfluorocarbon tail contain atleast four carbon atoms, and the preferred number is six to ten. Aterminal fluorocarbon chain of this minimum length is required in orderto insolubilize and render both hydrophobic and oleophobic theperfiuoroalkanesulfonamido end of the molecule. Increase in length ofthis tail decreases solubility still further and enhances the degree ofWater and oil repellency imparted to polymers of the present vinyl andallyl esters.

The length of the bridging alkylene group represented by 'R-- in thepreceding ester and acid formulas, which links the carboxylate group tothe sulfur-bonded nitrogen atom, can be varied to thereby modifysolubility and surface properties of the esters and their polymers, aswell as other physical properties of the polymers such as melting pointand flexibility. The N-substituted alkyl side group can also be employedand varied to modify properties.

Thus the general molecular structure of the present vinyl-type estercompounds can be varied to obtain polymerizable monomers havingspecifically different characteristics, so that monomers and polymershaving optimum properties for a given end use can be selected.

The esters may be employed as intermediates for making derivatives- Inparticular, the Vinyl group --provides a reactive terminal group thatcan be availed of in making derivatives as is well understood by thoseskilled in the vinyl'chemistry art. The esters may be employed assurface active agents, and may be used in unpolymerized form as surfacecoating or treating agents to impart a hydrophobic and 'oleophobiccharacteristic.

The esters may be employed as polymerizable monomers to form novelfluorocarbon homopolymers and heteropolymers containing a multiplicityof fluorocarbon ester units which each have a perfluorocarbon tail (Rcontaining from 4 to 12 fully fluorinated carbon atoms.

The skeletal stru'cture of the polymer molecule includes a recurringfluorocarbon ester unit of the following formula when the monomer is avinyl ester:

, (3H2 V nisommonobocn The following is the corresponding formula of therecurring fluorocarbon ester unit when the monomer is an allyl ester;

Copolymerization of our vinyl and allyl esters results in copolymersthereof that include both the above types of recurring fluorocarbonester units in the polymer molecule. 7 g 7 7 Bulk, solution and emulsionpolymerization procedures can be used, employing peroxide catalysts. V pThe, fully polymerized 'vinyl and allyl homopolymers are clear,colorless, water-repellent and oil-repellent,

Patented July 1, 1958.

3 thermoplastic solids. They are insoluble in hydrocarbons and innon-polar organic solvents and are highly insoluble in water. They aresoluble in fluorinated solvents, such as fluorocarbon acids and esters,benzotrifluoride, and xylene hexafluoride.

Coatings can be applied from solution or emulsion to provide firmlybonded surface coatings or sizings on cloth, paper, leather, glass andceramic articles, lithic materials, and metals. Due to orientation ofthe polymer molecules, the fluorocarbon tails provide an inert fluorocarbon-like outer surface which is both hydrophobic and oleophobic.Drops of water and drops of oil deposited on the surface will remain orrun off rather than spreading and wetting the surface. In treatingfibrous materials such as cloth and paper, the sizing need only besuflicient to provide an extremely thin coatin" on the fibers, whichdoes not appreciably affect the appearance, flexibility, strength orporosity of the material. The sized cloth or pare is rendered resistantto absorption and staining by oily or greasy materials, as well as beingrendered repellent to Water. Both oily and watery stains can be wipedoif.

In addition to homopolymers and copolymers made exclusively from theaforesaid vinyl and allyl ester monomers, novel copolymers(heteropolymers) may be made by interpolymerizing the present estermonomers with polymerizable monomers of other kinds which contain anethylenic linkage. Examples of the latter are maleic anhydride,acrylonitrile, vinyl chloride, vinyl acetate, vinyl silicones, styrene,methyl acrylate, methyl methacrylate, ethylene, isoprene and butadiene;both as to non-halogenated and halogenated varieties. This makespossible the production of many types of polymers having differentphysical properties, wherein the polymer molecules include fluorocarbonester units providing perfluorocarbon side-chain ta ls of the typementioned above.

The properties of the polymer masses can also be varied by the use ofplasticizers (such as fluorocarbon esters), and by compounding withcarbon black and other finely divided solid materials such as zincoxide. The stiffness or hardness of the polymer mass can be increased byincluding a small proportion of a polyfunctional compound at the time ofpolymerization to cause crosslinking between the skeletal chains andthereby form a three-dimensional network. The use of various expedientsfor modifying the properties of polymer masses is understood by thoseskilled in polymer chemistry and need not be elaborated upon.

The fundamental contribution of the present invention is the discoveryof the aforesaid novel fluorocarbon vinyl and allyl esters and of theirutility as polymerizable monomers for making novel and useful polymers.

The present vinyl-type esters are derivatives of the aforesaidperfluoroalkanesulfonamido alkylenemonocarboxylic acids, and may beprepared by esterification of such acids employed as starting compounds.These acids are described in some detail and are claimed in thecopending application of one of us, H. A. Brown, filed of even dateherewith, S. N. 556,047, and since issued as Patent No. 2,809,990 onOct. 15, 1957. The preferred process of making such acids is outlined bythe following equations showing the series of steps which can be used inderiving them from corresponding perfluoroalkanesulfonyl fluoridestarting compounds (the preparation of the latter by means of anelectrochemical fluorination process being described in the aforesaidcopending application of Brice and Trott, now Patent No. 2,732,398):

In the above formulas, R R and R have the same meanings as in previousformulas.

This process thus consists in preparing a perfluoroalkancsulfonamide,converting this to a sulfonamide salt, converting the latter to an esterof the desired acid which is then hydrolyzed to a salt of the acid, andhydrolyzing the salt to form the product acid.

The present vinyl-type esters can also be prepared as an intermediate inthe above reaction scheme and recovered as such, without making the acidcompound. This can be accomplished by employing the third step shownabove to prepare the desired vinyl or allyl ester derivative as, forexample, by reacting the sulfonamide salt with vinyl or allylchloroacetate.

The following experimental examples illustrate the preparation of thesubject compounds and polymers.

Example I A one liter flask was charged with 445 grams of N-etl1ylperfluorooctanesulfonamide, C F SO NHC H and addition was made of 19.4grams of sodium dissolved in 300 ml. of methanol. After mixing, most ofthe methanol was distilled off by heating under reduced pressure. Themethanol distillation was completed by adding 454 grams of benzene andheating under reduced pressure to remove the benzene. Then 204 grams ofvinyl chloroacetate, ClCH COOCH CH was added and the mixture was stirredfor 4 hours. After 64 hours standing at room temperature, the mixturewas refluxed for 2 hours and then filtered. Vacuum distillation andredistillation resulted in a 44% yield of a fraction having a boilingrange of 103-109 C. at 0.1 mm. The product was a white waxywater-repellent solid at room temperature, and was identified as thedesired vinyl ester:

Analysis showed 2.26% nitrogen (2.28% ca1c.). infrared spectralabsorption analysis was consistent.

Polymerization was effected by charging a heavywalled Pyrex glassampoule with 1.5 grams of this vinyl ester monomer and 0.015 gram ofacetyl peroxide (catalyst) dissolved in 0.060 gram of dimethyl phthalatesolvent. To remove any oxygen in the ampoule, thevinyl ester monomer wasmelted by warming the ampoule. Then the ampoule was frozen in liquidair, evacuated to a pressure of less than 0.1 mm., and sealed whilefrozen. The sealed ampoule was then warmed until the monomer was melted,and placed in an end-over-end rotator which was immersed in a water bathmaintained at 60 C. After 15% hours of agitation, the ampoule wasremoved and the contents was dissolved in xylene hexafluoride. Thesolution was poured into a large excess of methanol to precipitate thepolymer, which was filtered out and dried in a vacuum oven at roomtemperature, yielding 0.95 gram (64% yield). This polymer product was awhite thermoplastic powder having a softening point of approximately 70C. The inherent viscosity was 0.13

(determined from viscosity of a solution of 1.11 grams polymer per literof xylene hexafluoride solvent).

Example 2 A 250 ml. flask was charged with 51.3 grams of N-methylperfluorooctanesulfonamide, C F SO NHCH and addition was made of 2.3grams of sodium dissolved in 50 ml. of methanol. After mixing, most ofthe methanol was distilled off by heating under reduced pressure. Themethanol distillation was completed by adding 50 ml. of benzene andheating under reduced pressure to remove the benzene. After adding 50ml. of acetone and 2 grams of potassium iodide, addition was made of24.1 grams of vinyl chloroacetate. An almost immediate reaction wasnoted. The acetone mixture was refluxed overnight. The salt was filteredout and the mixture was washed with ether and then with water. The waterphase 5. bined and the ether evaporated 011? under reduced pressure. Theresidue of 45 grams was distilled under vacuum in a small Vigreauxcclumn. The cut boiling at 100-106 C. at. 0.2 mm. was recovered in ayield of 20.5 grams. This product was a white waxy water-repellent solidat room temperature and was identified a the desired vinyl ester:

Analysis showed 2.40% nitrogen (2.34% calc.). The infrared spectralabsorption analysis was consistent.

A sample of this vinyl ester monomer was polymerized in a manner similarto that described in the preceding example. A 64% yield of purifiedpolymer was obtained in the form of a white thermoplastic powder havinga softening point of 95100 C. The inherent viscosity was 0.12(determined from viscosity of a solution of 1 gram polymer per liter ofxylene hexafluoride solvent). A transparent colorless solid plastic masswas made by moistening the powdered polymer with acetone and drying tofuse the particles together and eliminate the acetone.

As illustrative of the utility of our polymers for sizing cloth toimpart both water repellency and resistance 7 to absorption and stainingby oily and greasy materials, the following tests are presented:

Samples of cotton jeans cloth were dipped into a 1% (by weight) solutionof the above polymer in xylene hexafluoride solvent and passed through asqueeze roll to remove excess saturant, followed by drying in an ovenfor 10 minutes at 150 C. Drops of water and drops of oil placed on thesurface of the treated cloth remained indefinitely without spreading outand wetting the surface. The high degree of water repellency was shownby a spray test (Standard Test Method No. 22-52 published in the 1952Technical Manual and Yearbook of the American Association of TextileChemists and Colorists, vol. XXVII, page 136), which gave a rating of 90as compared with 100 which is the highest possible test rating. It hasbeen found that a severe test of oil repellency is to determine theresistance to penetration by solutions of mineral oil in heptane, whichhave a greater tendency to penetrate than does mineral oil alone. Thehigher the proportion of heptane the quicker the penetration. In thecase of the above-mentioned treated cotton cloth, it was found thatresistance to penetration for at least 3 minutes was obtained with amineral oil solution containing 45% (by volume) of heptane, whichdemonstrated excellent resistance to oil.

Excellent water and oil repellency were also exhibited by a similarlytreated fabric which was a blend of 55% Dacron fibers and 45 worsted(Wool) fibers. (Dacron is the trademark of the Du Pont Company for drawnpolyester fibers produced from a polyester of ethylene glycol andterephthalic acid.)

Water and oil base stains (e. g., from ink, soft drinks, coffee, saladoil, gravy, hair oil, etc.) could be removed from the treated fabrics byblotting and rubbing without leaving a mark. Yet the treatment did notadversely affect the hand, shade, strength or porosity of the fabric andwas invisible in its effect except as to imparting a combinedhydrophobic and oleophobic character.

The insolubility of the polymers in water, hydrocarbons and commonorganic solvents renders the cloth sizing highly resistant to removalwhen subjected to such materials, and permits of laundering and of drycleaning sized fabrics without destroying the effectiveness of thesizing.

Fabrics can also be sized with the polymer in the form of an aqueouslatex dispersion, thereby avoiding the use of solvent vehicles.

Example 3 To a flask containing 23.0 grams of freshly distilled vinylacetate and 0.75 grams of mercuric acetate there 6 was added 23.5 gramsof N-methyl,- N-perfluorooctanea sulfonyl ll-aminoundecanoic acid,

, The mixture was heated to about 45 C. to form a solu-- tion and 0.15gram of concentrated sulfuric acid was added dropwise with stirring andshaking. As the solution cooled below 35 C. the acid precipitated out.The mixture was allowed to stand for 6 days at room temperature, andthen 1.0'gram of sodium acetate was added and the mixture was filtered.The volatiles were evaporated olf from the filtrate under reducedpressure and the residue was subjected to vacuum distillation.

yield of 6 grams. solid and was identified as the desired vinyl ester:

Analysis showed 45.0% fluorine (45.9% calc.) and 1.91% nitrogen (1.99%calc.). Infrared spectral absorption analysts was consistent.

Example 4 A 100 ml. flask provided with a 12 inch distillation columntopped with a Barrett trap was charged with 40 grams ofN-perfluorooctanesulfonyl glycine,

10 grams of allyl alcohol, CH =CHCH OH, 0.4 gram ofbeta-naphthalenesulfonic acid and 35 grams of toluene. The mixture washeated to reflux. The acid slowly dissolved in the toluene. About 2 ml.of water collected in the trap during 3 hours of refluxing. The benzenewas removed and the residue was fractionally distilled. The cut boilingat 137139 C. at 0.5 mm. was redistilled to yield 20 grams of productboiling at 121 C. at 0.175 mm., a light-colored waxy water-repellentmaterial having a melting point of 7075 C., which was identified as thedesired allyl ester:

C F SO NHCH COOCH CH=CH Example 5 Using a procedure essentially the sameas described in the preceding example, 10 grams of allyl alcohol wasreacted with 40 grams of N-methyl, N-perfiuorooctanesulfonylll-aminoundecanoic acid,

to obtain 23 grams of product boiling at 173180 C. at 0.05 mm., whichwas a white waxy water-repellent material at room temperature. It wasidentified as the desired allyl ester:

A copolymer of this allyl ester and maleic anhydride was prepared asfollows:

A 3-necked 50 ml. flask equipped with a stirrer, reflux condenser andgas inlet tube, was charged with 7.38 grams of the allyl ester, 0.98gram of maleic andydride, and 4.5 grams of toluene. With nitrogenflowing through the system the mixture was brought to reflux to removeoxygen from the system, and was then cooled under nitrogen at 60 C. and0.0836 gram of benzoyl peroxide was added. The nitrogen flow was stoppedand the temperature was raised to 70-73 C. by using an oil bath. Thereaction temperature was held at 70 C. for 24 hours, addition was madeof a further 0.0836 gram of benzoyl peroxide, and the reactiontemperature was raised to C. and held for 4 hours. Then the contents ofthe flask was poured into 50 grams of methanol and the precipitatedpolymer was filtered and air dried. The yield was 54%.

The polymer product was a crystalline mass which softened at 94 C. Itwas insoluble in water and in common organic solvents but was soluble inxylene hexafluoride and in mixtures of methyl ethyl ketone and xylenehexafluoride. It had an intrinsic viscosity of 0.04

The cut a boiling at l60166 C. at 0.175 mmrwas obtained in a It was awhite waxy water-repellent 7 (determined from viscosity of a solution of1 gram of polymer per liter of Xylene hexafiuoride' solvent).

We claim:

1. Fluorocarbon vinyl-type esters of the class consisting of vinylesters and allyl esters of perfiuoroalkanesulfonamidoalkylenemonocarboxylic acids; said vinyl esters having the formula:

R SO N(R)RCOOCH=CH and said allyl esters having the formula:

R SO N R' RCOOCH CH CH wherein R is a perfiuoroalkyl group containing 4to 12 carbon atoms, R is an alkylene bridging group containing S 1 to 12carbon atoms, and R is of the class consisting of a hydrogen atom andalkyl groups containing 1 to 6 carbon atoms.

2. Solid polymers of fluorocarbon vinyl-type esters specified in claim1.

3. Articles which have been coated or sized with solid polymers offluorocarbon vinyl-type esters specified in claim 1.

4. Fabrics which have been sized with solid polymers of the vinyl estersspecified in claim 1 so as to have been rendered both Water repellentand oil repellent.

No references cited.

1. FLUOROCARBON VINYL-TYPE ESTERS OF THE CLASS CONSISTING OF VINYLESTERS AND ALLYL ESTERS OF PERFLUOROALKANESULFONAMIDOALKYLENEMONOCARBOXYLIC ACIDS; SAID VINYL ESTERS HAVING THE FORMULA: